Yes / Bioarchaeological and clinical data show that diet influences health, and this relationship is crucial to how we understand past health with respect to sex and age. We propose a new method that coinvestigates the relationship between mortality risk and diet in the past. Our method integrates dietary stable isotope data (δ13 Carbon and δ 15 Nitrogen) from Roman Britain (N=659) with hazards analysis. The results show that these data can be informatively used in this type of analysis in general, and that in the context of Roman Britain, higher δ 13C is associated with lower risks of mortality while higher δ 15N is associated with elevated risks of mortality. Importantly, the results emphasize that a bioarchaeological approach to interpretation must be taken in order to more fully understand the results obtained by the method

Yes / In this study, period-specific dietary trends, along with socio-economic and religious influences on foods consumed by Pictish and medieval inhabitants from Portmahomack are investigated. Bone collagen from human adults (n = 137) and fauna (n = 71) were analysed for stable carbon and nitrogen isotope ratios to enable dietary reconstructions of the whole adult skeletal assemblage. Adult mean δ13C and δ15N values from all periods (6th to 17th century) were −19.5‰ ± 1.3‰ and 13.3‰ ± 1.7‰ respectively. A diachronic change in diet between early medieval Pictish lay and monastic communities (periods 1–3) and the later medieval parish layfolk (periods 4–5) was found that suggests changing socio-economic and religious influences, along with age and gender differences in diet that reflect possible divisions in labour and status. Faunal data also reflected a diachronic change in diet, most likely related to a change in animal husbandry practices over time. This is the first large-scale study on the Portmahomack assemblage and presents new isotope data to provide a more comprehensive insight into Pictish and medieval subsistence patterns, along with evidence of how religious and social foci may influence diet over time. Such comprehensive investigations can only be adopted by analysing the whole skeletal assemblage, providing robust faunal baselines and inter- and intra-site comparisons. Most importantly, this significant new evidence fundamentally changes our knowledge of diet and subsistence in medieval Scotland and the potential influences therein. / Supported by grants from the NERC Isotope Geosciences Facility Steering Committee (IP‐1302‐0512), the Arts and Humanities Research Council (AH/I019103/1), and Historic Scotland (AMJ/4208/4).

Yes

Yes / The study presents results of the investigations of diet based on carbon and nitrogen stable isotope ratios (δ13C and δ15N) of the bone collagen of individuals buried in medieval elite chamber graves from the territory of the state of the first Piasts, Poland (the second half of the 10th and the first half of the 11th century). The aim of the research was to determine the diet of individuals buried in such funerary structures, to compare this with commoners buried in ordinary graves, and investigate any sex-related patterns. Rib bone samples were taken from individuals buried in chamber graves at Bodzia, Dziekanowice, Pień and Sowinki. Results indicate that the elite male diet was based on C3 plants with possible contribution of some C4 plants (millet) and substantial consumption of animal proteins including fish. The bone collagen δ13C and δ15N of male chamber burials suggested consumption of higher trophic level foodstuffs (meat and fish) whilst the female diet, and that of the juveniles, was similar to the commoners in the rest of the population.

Washington, D.C. is a city that is designed to serve an entire nation; yet, as a result of this, its own history and people can seem to be lost in the shadow of the federal city. With an abundance of museums throughout the city, the museum that is needed, but no longer exists, is one for the District itself. This omissionleaves a tremendous gap in historical knowledge and no representation focused on the character of the city itself. How can we fulfill this need in a way that is unique to this specific city and would provide more than an exhibit by allowing people to be surrounded by and contribute to the accumulated evolution of their history? Adaptive reuse encourages the gradual unearthing of historical inspiration, which allows representation of existing and past local populations. For my thesis, I sought to fulfill this need by turning to the existing fabric of the city, learning from it, and eventually employing adaptive reuse techniques to unify the existing framework with the new program. / Master of Architecture / In a city such as Washington, D.C., which is filled with history and which focuses on historical knowledge and representation, the history and fabric of the city itself can seem to be overshadowed. By looking at the existing character of D.C. and its architecture as the foundation and using adaptive reuse techniques, the neighborhoods could be brought to the forefront and the true backbone of D.C. could shine. This would better represent a city that has been much more than a tourist attraction, but a home, and thus represent the people who have created this rich history. The people within the District need an outlet to regain ownership of their history, create a place to learn about their city, and share what makes the larger District so unique. For my thesis, I sought to explore this history and provide this outlet by repurposing an existing building within the city.

West Back Bay in Biloxi, Mississippi is an oligohaline estuary. Salt-tolerant submerged aquatic vegetation (SAV) and saltmarsh grasses are found ubiquitously throughout this estuary with Vallisneria americana and Juncus roemerianus being the dominant SAV and saltmarsh vegetation. No studies have directly evaluated the role of these vegetation species in the food web. Carbon and sulfur stable isotope analyses were used to identify primary source contributions to fishes Menidia beryllina, Fundulus grandis, and Lepomis macrochirus. Isotopic niche overlap was compared between fishes and basal carbon sources bimonthly from May 2021 through May 2022. Fishes had greater than 50% isotopic niche overlap with SAV compared to fringing saltmarsh. Overlap was less than 23% for Juncus roemerianus and negligible for other saltmarsh species. These results suggest that Vallisneria americana in Back Bay is a primary driver of these fishes’ diets and should be a focus of habitat conservation efforts in oligohaline ecosystems.

Food web structure is of underlying importance to ecological functions and processes. Whilst it is understood that a range of biotic and abiotic factors affect structure, relatively little is known of the role of biodiversity per se in structuring food webs. In this thesis I utilise novel multi-dimensional estimates of food web structure based on stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) to quantify structural responses to changing community diversity. I additionally investigate methodological aspects of sample preparation and stable isotope quantifications of food chains. Using an arthropod prey-predator system, in chapter 2 I demonstrate that tissue selection and lipid extraction are important methodological procedures for deriving accurate δ15N and δ13C signatures. In chapter 3 I test the utility of δ15N to quantify food chain length, and δ13C to trace primary energy sources through to end consumers. Bayesian resampling of variance in sample means for plant and arthropod food chains produces robust isotopic estimates that match known food chain length well despite some error variance, and estimates of δ13C-range that trace trophic transfers. Chapter 4 represents a change in system from lab to field as I determine δ15N and δ13C signatures for plant and invertebrate species within three grassland communities representing a gradient of biodiversity. Quantifications of community bivariate isotopic space using isotopic metrics revealed that greater taxonomic richness increased both diversity of resource space exploited and overlap in resource space. These results therefore suggest that loss of diversity affected structure through altering relative patterns of niche partitioning in resource exploitation amongst community members. In chapter 5, I additionally find evidence that grassland management mediated changes in food web compartmental structure that were associated with differences in generalist invertebrate predator feeding habits. Taken together, these findings develop and demonstrate the utility of isotopic approaches to quantifying food web structure, and provide evidence of important mechanisms by which biodiversity affects food web structure. I conclude that the preservation of natural food web structure and trophic dynamics are further reasons for halting loss of biodiversity.

Cette thèse comporte trois parties indépendantes. La première traite des formes fermées de la factorisation de Wiener-Hopf pour les processus de Lévy. Nous recensons la demie-douzaine de cas pour lesquels la factorisation peut être écrite explicitement, et mettons l'accent sur les fonctions méromorphes ayant des pôles d'ordre deux. La deuxième partie se focalise sur l'inversion de la transformée de Laplace. Son but est de présenter une nouvelle méthode approximative, dans un contexte probabiliste. Si la transformée de Laplace a un comportement facilement identifiable en zéro et si la densité associée est bornée, alors cette méthode permet d'obtenir une borne uniforme pour l'erreur commise sur la fonction de répartition. L'efficacité de cette méthode est testée sur deux exemples non triviaux. Enfin, la troisième et dernière partie est dédiée au pricing d'options exotiques dans le modèle log-stable aux moments finis de Carr et Wu. Dans certains cas, il est possible d'obtenir des formules fermées sous forme de séries convergentes pour les prix d’options lookback et barrières. Pour tous les autres cas, nous étudions divers techniques de simulation pour les trajectoires du processus sous-jacent, dans le but d'une évaluation par méthode de Monte-Carlo. / This thesis consists of three independent chapters.The first one deals with closed forms of the Wiener-hopf factorization for Lévy processes. We list the known cases for which this factorization can be explicitely written and provide a detailed account when the underlying functions are meromorphic of order two.The second chapter focuses on the inversion of the Laplace transform. We present an approximative method in a probabilistic setting. If the behavior of the Laplace transform near zero is known and if the underlying density is bounded, then this method yields a uniform bound for the error on the cumulative distribution function. We test this technique on two non-trivial examples.The final chapter of the thesis is dedicated to the pricing of exotic options in the Finite Moment Log-Stable model of Carr and Wu. In some cases, it is possible to obtain closed forms (converging series) for the prices of lookback and barrier options. In all other cases, we study several simulation techniques for the trajectories of the underlying for the purpose of Monte-Carlo valuation.

Dans cette thèse, on considère une équation différentielle stochastique gouvernée par un processus de Lévy de saut pur dont l’indice d’activité des sauts α ∈ (0, 2) et on observe des données haute fréquence de ce processus sur un intervalle de temps fixé. Cette thèse est consacrée tout d’abord à l’étude du comportement de la densité du processus en temps petit. Ces résultats permettent ensuite de montrer la propriété LAMN (Local Asymptotic Mixed Normality) pour les paramètres de dérive et d’échelle. Enfin, on étudie des estimateurs de l’indice α du processus.La première partie traite du comportement asymptotique de la densité en temps petit du processus. Le processus est supposé dépendre d’un paramètre β = (θ,σ) et on étudie, dans cette partie, la sensibilité de la densité par rapport à ce paramètre. Cela étend les résultats de [17] qui étaient restreints à l’indice α ∈ (1,2) et ne considéraient que la sensibilité par rapport au paramètre de dérive. En utilisant le calcul de Malliavin, on obtient la représentation de la densité, de sa dérivée et de sa dérivée logarithmique comme une espérance et une espérance conditionnelle. Ces formules de représentation font apparaître des poids de Malliavin dont les expressions sont données explicitement, ce qui permet d’analyser le comportement asymptotique de la densité en temps petit, en utilisant la propriété d’autosimilarité du processus stable.La deuxième partie de cette thèse concerne la propriété LAMN (Local Asymptotic Mixed Normality) pour les paramètres. Le coefficient de dérive et le coefficient d’échelle dépendent tous les deux de paramètres inconnus et on étend les résultats de [17]. On identifie l’information de Fisher asymptotique ainsi que les vitesses optimales de convergence. Ces quantités dépendent de l’indice αLa troisième partie propose des estimateurs pour l’indice d’activité des sauts α ∈ (0,2) basés sur des méthodes de moments qui généralisent les résultats de Masuda [53]. On montre la consistence et la normalité asymptotique des estimateurs et on illustre les résultats par des simulations numériques / In this thesis, we consider a stochastic differential equation driven by a truncated pure jump Lévy process with index α ∈(0,2) and observe high frequency data of the process on a fixed observation time. We first study the behavior of the density of the process in small time. Next, we prove the Local Asymptotic Mixed Normality (LAMN) property for the drift and scaling parameters from high frequency observations. Finally, we propose some estimators of the index parameter of the process.The first part deals with the asymptotic behavior of the density in small time of the process. The process is assumed to depend on a parameter β = (θ,σ) and we study, in this part, the sensitivity of the density with respect to this parameter. This extends the results of [17] which were restricted to the index α ∈ (1,2) and considered only the sensitivity with respect to the drift coefficient. By using Malliavin calculus, we obtain the representation of the density, its derivative and its logarithm derivative as an expectation and a conditional expectation. These representation formulas involve some Malliavin weights whose expressions are given explicitly and this permits to analyze the asymptotic behavior in small time of the density, using the self-similarity property of the stable process.The second part of this thesis concerns the Local Asymptotic Mixed Normality property for the parameters. Both the drift coefficient and scale coefficient depend on the unknown parameters. Extending the results of [17], we compute the asymptotic Fisher information and find that the rate in the Local Asymptotic Mixed Normality property depends on the index α.The third part proposes some estimators of the jump activity index α ∈ (0,2) based on the method of moments as in Masuda [53]. We prove the consistency and asymptotic normality of the estimators and give some simulations to illustrate the finite-sample behaviors of the estimators

De nombreux écosystèmes forestiers français sont développés sur des sols acides et pauvres en éléments nutritifs. Dans de nombreux contextes, la fertilité minérale de ces sols forestiers se dégrade lentement, en lien notamment avec des pressions extérieures passées ou actuelles (e.g. diminution des apports atmosphériques de nutriments, augmentation des exportations de biomasse). Ce constat préoccupe la communauté forestière et des solutions de restauration/remédiation sont souvent envisagées. L’amendement avec un produit carbonaté est une pratique connue pour réduire l'acidité du sol, améliorer le fonctionnement global de l'écosystème et compenser les pertes de nutriments causées par la récolte de biomasse. Cependant, les effets de l’amendement sur les processus et le cycle biogéochimique du calcium et magnésium dans les écosystèmes forestiers sont peu connus à ce jour. Cette étude se focalise sur le devenir du magnésium et du calcium provenant de la dissolution des produits d’amendement dans cinq hêtraies situées dans le nord de la France sur une période allant jusqu’à 45 ans après l’apport. Pour cela, les approches élémentaires « conventionnelles » ont été combinées avec une approche multi-isotopique (26/24Mg, 44/40Ca et 87/86Sr). Les données provenant des parcelles témoins mesurées tout au long de la période d'étude suggèrent, quel que soit le site considéré, que les pools échangeables de cations nutritifs dans le sol ont diminué sur les dernières décennies et que cette tendance, associée à la faible richesse chimique du sol, se reflète dans la nutrition foliaire (Ca, Mg, K, P). En comparaison des placettes témoins, les pools échangeables de Mg et de Ca dans l’horizon 0-40 cm du sol ont augmenté dans les placettes amendées durant la première décennie après l’amendement, mais les différences s’estompent après 20 à 30 ans. Cependant, l'effet de l’amendement sur la nutrition des arbres est encore observé 40 ans après l’apport, très probablement parce que le cycle biologique de ces éléments a été dynamisé par l’amendement. La réponse des écosystèmes à l’amendement varie d'un site à l'autre, en fonction de la nature du produit (CaCO3 ou Ca-MgCO3) et du niveau de richesse chimique initial du sol, les sites les plus pauvres chimiquement enregistrant les réponses les plus marquées. Les variations naturelles des rapports isotopiques du Mg, Ca et Sr, en complément des approches conventionnelles, mettent en évidence l’importance de la composante Bio des cycles biogéochimiques du Ca et Mg dans ces hêtraies à faible fertilité minérale. Ces outils isotopiques ont également permis de démontrer l'incorporation durable de Ca et Mg issus des produits d’amendement dans leur cycle biologique respectif et de mettre en évidence des modifications de fonctionnement biogéochimique des écosystèmes suite à l’amendement / In France, many forest ecosystems grow on acidic and nutrient poor soils. In numerous cases, the chemical fertility of forest soils is slowly degrading due to increasing external pressures (e.g. decreasing atmospheric inputs, increasing biomass exportations) and is a growing concern in the international forest community. Forest management often must resort to restauration/remediation practices to ensure the sustainability of the ecosystem. Forest liming with a carbonate product is a known practice to reduce soil acidity, globally improve the ecosystem functioning and compensate nutrient losses caused by biomass harvest and exportation. However, our understanding of the effects of liming on magnesium and calcium biogeochemical processes and cycling in forest ecosystems is still incomplete. This study focuses on the fate of magnesium and calcium originating from the dissolution of liming products in the soils and trees of five beech forests located in Northern France over a period up to 45 years. In order to do so, “conventional” total-element approaches were combined with a multi-isotopic approach (26/24Mg, 44/40Ca et 87/86Sr). At all five sites, the data measured in control plots throughout the study period suggest that the exchangeable pools of nutrient cations in the soil has decreased over the last several decades and that this trend, together with the low chemical fertility level of the soil, was reflected in foliar nutrition (Ca, Mg, K, P). Compared to the control plots, soil exchangeable pools of Mg and Ca in the 0-40cm layer in the limed plots increased during the first decade after liming but differences were no longer observable in soil pools after 20 to 30 years. However, the effect of liming on tree nutrition was still observed after 40 years, most probably because the biological cycling of these elements was enhanced by the lime input. The ecosystem response to the lime input varied between sites depending on the nature of the liming product (CaCO3 or Ca-MgCO3) and the initial chemical fertility level of the soil, the poorest sites showing the strongest responses. The natural variations of Mg, Ca and Sr isotopic ratios combined with conventional approaches highlight the importance of the BIO component of the biogeochemical cycling of Mg and Ca in the studied low chemical fertility beech forests. These isotopic tools also enabled to show the long-lasting incorporation of the Mg and Ca released from the liming product in the biological cycle and highlight the changes in the biogeochemical functioning of these forest ecosystems after the liming operation